A roof support of this type is found, for example, in AT-PS 379 215. In roof supports of this type, the lemniscate mechanism works in such a way that when the roof bar is being raised, it moves in a largely vertical direction. In roof supports of this type, the principle of arranging the props at an angle to one another with, e.g., four props being used to connect the base frame to the roof bar, is known in the art. Such roof supports can be moved on runners or caterpillar tracks, for example. When these roof supports are used in room-and-pillar coal-mining, they have to support high roofs, and therefore under unfavorable load conditions the lemniscate mechanism has to cope with great lateral forces. Particularly with fully extended props and very high roofs, such lateral forces can cause overloading of the lemniscate mechanism, leading subsequently to the need for extensive repair work, with the entire lemniscate mechanism having to be completely replaced.